A pair of classic Japanese achros, both 1000mm and over 30 years age. I keep them as original as possible, adding a Telrad base and dew strip to each. Both have been stripped down, cleaned and put back to restore.
The 90 M is f11 and came with a teak tripod and az mount. It is lovely with solar and distance terrestrial observing.I kept the focusers as they are smooth r&p with no backlash. The 102 SP is just under f9.5, ca and spherical abberation are not problems. Collimation is set at the factory. Taking the objectives out , there is a pencil line across the sides. Line these up to get the best results, just little touches in the factory are what classic gear is about ! The dew shields and lens covers push on gently and stay there , just lovely close tolerance engineering.
The 102 came with a motorised Super Polaris mount . It was severely neglected with white deposits in the dew shield. The baffling down the tube is very impressive. Both scopes give plenty of colour and needle sharpness. They come up now and again for sale, different from some of the mass produced achros that can be found nowadays.
4″ clear aperture presents the most efficient image and around this mark it certainly is the case. There is a new 4″ f13 scope from Bresser ( Meade ) ,a thing of beauty that I can’t wait to try. Nick.